<div>
  <let/id=0/>
  <let/items=[]/>

  <for|item| of=items>${item}</for>

  <button id="add" onClick() { 
    // TODO: nested writes ([...items, id++]) don't work
    const nextId = id + 1;
    id = nextId;
    items = [...items, nextId];
  }>Add</button>
  <button id="remove" onClick() { items = items.slice(0, -1); }>Remove</button>
</div>
